As far as I'm concerned, the MySQL driver is only tested against
MySQL 4.1 - with pretty much a default build - and on Linux and
FreeBSD platforms. In principle that shouldn't make any difference,
but in practice I don't know.

So I build with MySQL 4.1.15 and running with the 4.1.15 libmySQL.dll .

And after setting the directives higher, I got it working better:

DBDMin 10
DBDKeep 32
DBDMax 64

That runs fine fine, but after a few hours all connectons are lost with the backend and had to restart Apache.

Bottom line for me:
It is hardly tested on win32 and I believe they did not made it thread-safe (common issue with other mods using mySQL). I am not going to use it for the time being.

You would think that someone would have paid attention to what open-source and popular database systems are doing. MySQL took a lot of time developing version 5. They started releasing alpha code it seems like a year and half ago or more, and whitepapers well before that.

I guess that's the reason for different vantage points, and where forums are useful. Sometimes when you're inside you seem to never be able to see it from outside.